diff options
| author | Dmitry Safonov <dima@arista.com> | 2018-11-01 00:24:47 +0000 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-01-23 08:10:52 +0100 |
| commit | b4ff011f6748d5bfb217abce7055a6101e443322 (patch) | |
| tree | 7e25113ecd568a4a341174b4d5b3e483632f6e7e /fs/proc/array.c | |
| parent | 6e8dba394f06e9c84f89ed0284825f67720bb3a3 (diff) | |
tty: Hold tty_ldisc_lock() during tty_reopen()
commit 83d817f41070c48bc3eb7ec18e43000a548fca5c upstream.
tty_ldisc_reinit() doesn't race with neither tty_ldisc_hangup()
nor set_ldisc() nor tty_ldisc_release() as they use tty lock.
But it races with anyone who expects line discipline to be the same
after hoding read semaphore in tty_ldisc_ref().
We've seen the following crash on v4.9.108 stable:
BUG: unable to handle kernel paging request at 0000000000002260
IP: [..] n_tty_receive_buf_common+0x5f/0x86d
Workqueue: events_unbound flush_to_ldisc
Call Trace:
[..] n_tty_receive_buf2
[..] tty_ldisc_receive_buf
[..] flush_to_ldisc
[..] process_one_work
[..] worker_thread
[..] kthread
[..] ret_from_fork
tty_ldisc_reinit() should be called with ldisc_sem hold for writing,
which will protect any reader against line discipline changes.
Cc: Jiri Slaby <jslaby@suse.com>
Cc: stable@vger.kernel.org # b027e2298bd5 ("tty: fix data race between tty_init_dev and flush of buf")
Reviewed-by: Jiri Slaby <jslaby@suse.cz>
Reported-by: syzbot+3aa9784721dfb90e984d@syzkaller.appspotmail.com
Tested-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Signed-off-by: Dmitry Safonov <dima@arista.com>
Tested-by: Tycho Andersen <tycho@tycho.ws>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'fs/proc/array.c')
0 files changed, 0 insertions, 0 deletions